The present invention relates to a gas generator for an air bag apparatus mounted in a vehicle or the like for protecting an occupant therein by inflating the air bag between the occupant and a constituent member of the vehicle at the time of collision of the vehicle, and the present invention also relates to an inflating method of the air bag.
A conventional air bag apparatus comprises a gas generator and an activate signal generating circuit for judging a degree of a collision detected by a collision sensor to activate an activating apparatus of the gas generator. As such a gas generator, there exist a solid propellant burning type gas generator, an inert gas accumulating type gas generator, an accumulating flammable gas burning type gas generator, and a hybrid type gas generator comprising the solid propellant burning type gas generator and the accumulating flammable gas burning type gas generator.
At the time of collision of the vehicle, if the activate signal is applied to the activating apparatus of the gas generator, an ignition section which is a part of the activating apparatus is heated, and when the ignition section is a squib, priming is exploded by the squib, and gunpowder charged in the vicinity of the priming is ignited.
In the case of the solid propellant burning type gas generator, a gas generating agent is ignited by thermal energy generated at that time, and the gas generating agent is burnt at a previously designed speed to generate burnt gas.
In the case of the inert gas accumulating type gas generator, a sealing plate of an accumulated gas vessel is similarly opened by explosion pressure of a trigger device, and the gas is generated at a previously designed speed.
In the case of each of the accumulating flammable gas burning type gas generator and the hybrid type gas generator, the accumulated gas itself is burnt by a trigger device or an ignition merely having a heating portion, and the burnt gas is generated at a previously designed speed.
Usually, timing for generating the activate signal is previously programmed such that the signal is generated when the vehicle collides against an obstruction such as a wall at a normal running speed (25 to 60 km/h). In this case, this timing is programmed on condition that an occupant having a predetermined weight, height and the like sits on a predetermined sitting position. Further, in any of the gas generators, the air bag apparatus is designed such that the air bag is inflated and developed within a short time such as about 40 to 50 ms so that it is possible to prevent the occupant from crashing into a steering wheel or a dashboard and from being damaged physically.
However, in any of the above-described conventional air bag apparatuses, since the inflating manner of the air bag is constant, when the sitting position and the physical condition are different from the predetermined condition, especially when the occupant is a child or a low occupant, it is reported lately that so far from protecting the occupant, the air bag may damage the occupant. Therefore, it is desirable to realize an air bag apparatus capable of controlling the inflation characteristics of the air bag in accordance with various conditions such as a physical condition and a sitting position of the occupant, a vehicle speed and the like.
The present invention has been accomplished to solve such a conventional problem, and it is an object of the invention to provide an accumulating flammable gas burning type gas generator for an air bag apparatus capable of controlling an amount of flammable gas, injection timing of flammable gas and the like.
According to a first aspect of the present invention, there is provided a gas generator for an air bag apparatus comprising charging means which is sealed after a flammable fluid is charged, a first chamber accommodating the charged flammable fluid and having a first vent opening occluded by a first occluding member, a second chamber accommodating a flammable fluid and having a volume greater than that of the first chamber and having a second vent opening occluded by a second occluding member which is capable of being in communication with the first chamber, at least one communication hole formed in a portion of a wall forming the first chamber and bringing the first and second chambers into communication with each other, first ignition means for igniting the flammable fluid in the first chamber, second ignition means for igniting the flammable fluid in the second chamber, and a diffuser which can be in communication with the first chamber through the first vent opening. By combining the ignition timings of the plurality of ignition means to control the injection speed of the burnt gas, it is possible to inflate and develop the air bag optimally so as to meet various conditions.
According to a second aspect of the invention, there is provided a gas generator for an air bag apparatus comprising charging means which is sealed after a flammable fluid is charged, a single chamber accommodating the charged flammable fluid and having a vent opening occluded by an occluding member, first and second ignition means for igniting the flammable fluid at different positions, an ignition preliminary chamber formed such as to surround the first ignition means and having at least one communication hole which is in communication with the single chamber, and a diffuser which can be in communication with the single chamber through the vent opening. By combining the ignition timings of the plurality of ignition means to control the injection speed of the burnt gas, it is possible to inflate and develop the air bag optimally so as to meet various conditions.
According to a third aspect of the invention, the gas generator further comprises an ignition preliminary chamber formed such as to surround the second ignition means and having at least one communication hole which is in communication with the second chamber. In addition to the first aspect, it is possible to swiftly burn the flammable fluid by the ignition preliminary chamber.
According to a fourth aspect of the invention, the gas generator further comprises an ignition preliminary chamber formed such as to surround the second ignition means and having at least one communication hole which is in communication with the single chamber. In addition to the second aspect, it is possible to swiftly burn the flammable fluid by the ignition preliminary chamber.
According to a fifth aspect of the invention, there is provided a gas generator for an air bag apparatus comprising first gas generating means, a second gas generating means and a diffuser, wherein each of the first and second gas generating means comprises charging means which is sealed after a flammable fluid is charged, a single chamber accommodating the charged flammable fluid and having a vent opening occluded by an occluding member, and ignition means for igniting the flammable fluid in the single chamber, wherein the diffuser is capable of being in communication with the single chambers through the vent openings respectively. Accommodating volumes and charging pressure of gases of the two gas generating means and gas components are set equal to or different from each other, and activating timings of the two ignition means are combined so as to control the injection amount, the injection speed and the like of the burnt gas, it is possible to inflate and develop the air bag optimally so as to meet various conditions.
According to a sixth aspect of the invention, there is provided a gas generator for an air bag apparatus comprising first gas generating means, a second gas generating means and a diffuser, wherein each of the first and second gas generating means comprises charging means which is sealed after a flammable fluid is charged, a single chamber accommodating the charged flammable fluid and having a vent opening occluded by an occluding member, ignition means for igniting the flammable fluid in the single chamber, and an ignition preliminary chamber formed such as to surround the ignition means and having at least one communication hole which is in communication with the single chamber, wherein the diffuser is capable of being in communication with the single chambers through the vent openings respectively. Accommodating volumes and charging pressure of gases of the two gas generating means and gas components are set equal to or different from each other, and activating timings of the two ignition means are combined so as to control the injection amount, the injection speed and the like of the burnt gas, it is possible to inflate and develop the air bag optimally so as to meet various conditions.
According to a seventh aspect of the invention, there is provided a gas generator for an air bag apparatus comprising first gas generating means, a second gas generating means and a diffuser, wherein each of the first and second gas generating means comprises charging means which is sealed after a flammable fluid is charged, a single chamber accommodating the charged flammable fluid and having a vent opening occluded by an occluding member, and ignition means for igniting the flammable fluid in the single chamber, wherein the second gas generating means comprises an ignition preliminary chamber formed such as to surround the ignition means and having at least one communication hole which is in communication with the single chamber, and the diffuser is capable of being in communication with the single chambers through the vent openings respectively. Accommodating volumes and charging pressure of gases of the two gas generating means and gas components are set equal to or different from each other, and activating timings of the two ignition means are combined so as to control the injection amount, the injection speed and the like of the burnt gas, it is possible to inflate and develop the air bag optimally so as to meet various conditions.
According to an eighth aspect of the invention, volumes of the single chambers of the first and second gas generating means, gas pressure of the flammable fluids charged in said single chambers of the first and second gas generating means, or gas components of the flammable fluids charged in said single chambers of the first and second gas generating means are substantially the same. By controlling the volume of the vessel, the pressure of the flammable fluid and the composition of the flammable fluid, it is possible to control the injection amount and the injection speed of the burnt gas.
According to a ninth aspect of the invention, volumes of the single chambers of the first and second gas generating means, gas pressure of the flammable fluids charged in said single chambers of the first and second gas generating means, or gas components of the flammable fluids charged in said single chambers of the first and second gas generating means are substantially different from each other.
According to a tenth aspect of the invention, the flammable fluid includes fuel gas, oxdizer gas and inert gas. Therefore, it is possible to use a flammable fluid which is easily available.
According to an eleventh aspect of the invention, only one of the ignition means is allowed to ignite. By igniting only one of the ignition means, it is possible to control the injection amount, the injection speed and the like of the burnt gas, and it is possible to inflate and develop the air bag optimally so as to meet various conditions.
According to a twelfth aspect of the invention, ignition timings of the two ignition means are different from each other. By controlling the ignition timing, it is possible to control the injection amount, the injection speed and the like of the burnt gas, and it is possible to inflate and develop the air bag optimally so as to meet various conditions.
According to a thirteenth aspect of the invention, ignition timings of the two ignition means are the same. By controlling the ignition timing, it is possible to control the injection amount, the injection speed and the like of the burnt gas, and it is possible to inflate and develop the air bag optimally so as to meet various conditions.
According to a fourteenth aspect of the invention, there is provided an inflating method of an air bag using the gas generator described in any one of claims 1, 2, and 5 to 7. By controlling the ignition timing, it is possible to control the injection amount, the injection speed and the like of the burnt gas, and it is possible to inflate and develop the air bag optimally so as to meet various conditions.